Problem: Solve for $y$ : $3 + y = -13$
Answer: Subtract $3$ from both sides: $ \begin{eqnarray} \\ 3 + y &=& -13 \\ \\ {-3} && {-3} \end{eqnarray} $ $ \begin{eqnarray} \hphantom{3 + y} &\hphantom{=}& \hphantom{-13} \\ y &=& -13 {- 3} \\ \end{eqnarray} $ Simplify. $ y = -16$